The purpose of this project is to study samples from cancer patients to determine the presence of bacteria, mycoplasma, fungi, and viruses which cause infection. Surveillance cultures which are taken upon admission of the patient to the hospital provide a baseline of the patients' flora. Carriers of pathogenic or highly resistant organisms can then be isolated. Repeated surveillance cultures from high risk patients allow determination of hospital acquisition of potential pathogens. Sources of hospital acquired microorganisms can thus be sought and eliminated. Environmental cultures provide further information as to possible sources of hospital-acquired microorganisms through detection of "shedders", efficacy of cleaning procedures, and unexpected contaminated sources. A total of 18,280 patient and environmental samples were cultured during the period of 4/1/77-3/31-78 for the presence of bacteria, mycoplasma, and fungi. In addition, 239 samples were cultured for viruses, 54 electron microscopic studies were performed to detect virus, and 3,624 serum samples were examined to detect rises in antibody titers against viruses. A serum bank which collected 7,872 sera from cancer patients for these and other research purposes were collected.